1. Field of the Invention
The invention relates in general to kits of tools and tools for use in erecting heavy objects, and, more particularly, embodiments of the present invention relate to kits of tools and tools for attaching tower segments to lifting devices.
2. Description of the Prior Art
Weld mounted free swiveling and pivoting hoist rings had been previously proposed. See, for example, Alba U.S. Pat. No. 6,953,212, which is hereby incorporated herein in its entirety as though fully set forth hereat.
Wind turbine towers, for example, are typically erected by bolting together a vertical array of frusto-conical tower segments. Each tower segment is typically elongated and has a generally circular mounting ring at each end. These mounting rings include mounting holes arrayed in a circular pattern to accommodate fastening bolts or screws. During erection, the mounting rings on the adjacent ends of mating tower segments are fastened together by means of bolts or studs extended through mating holes in adjacent tower segments. The mating rings are thus bolted together. The mounting rings in different tower segments, and different towers frequently have different hole sizes and hole spacing. Each tower segment is typically manufactured at a fabricating facility, transported to the site of erection, and then hoisted upright, and bolted to adjacent tower segments in a frusto-conical shaped vertical array. Tower segments are typically as much as 10 to 20 feet in diameter, 30 to 50 feet long, and weigh as much as from 80 to 100 tons. Hoisting a tower segment into an installed position requires that both ends of the tower segment be lifted off a transport vehicle or support structure, and then the upper end be hoisted until the tower segment is approximately vertical. The vertically supported tower segment must be accurately positioned and then bolted into place. Large capacity cranes are typically employed to hoist and position the tower segments. Such cranes are attached to the tower segments by way of cables, chains, webs, or the like lifting lines.
Tools that are used for attaching lifting lines to tower segments are typically attached to the mounting rings. Such tools must be safe, reliable, easy to use, and adjustable to accommodate various bolt hole sizes and spacings in different mounting rings. Such tools must also make provisions for adapting to the differences in the requirements for such tools depending on whether they are to be attached to the tops or the bottoms of the tower segments. Such tools should safely and easily accommodate all of the mounting hole sizes and spacings that may be found from one tower segment to another and from one tower to another.
Previously proposed expedients for tools that are used for attaching lifting lines to mounting rings include, for example, Storgaar, U.S. Publication No. 2009/0107062, published Apr. 30, 2009, which is hereby incorporated herein by reference in its entirety as though fully set forth hereat. The prior art devices and methods are not without their shortcomings. A major shortcoming of certain prior art devices and methods is the difficulty in adjusting the prior art tools to safely accommodate different hole sizes and spacings in the structures to which the tools are mounted. Complicated adjusting expedients tended to compromise the reliability and safety of the tools. Further, if mounted incorrectly certain prior art tools could bend or break during a lifting operation. The need for tools that are safe, reliable, rugged, simple to use, and to manufacture had been recognized by those concerned with these matters.
Lifting tools find utility wherever there are heavy objects to be lifted. Frequently, the opposed ends of a heavy object need to be lifted independent of one another to change the orientation of the object between vertical and horizontal. Embodiments of the present lifting tool kits find particular application where both ends of an object need to be hoisted to change the object's orientation. For example, some large heavy objects such as storage tanks, towers, reactors, structural members, and the like are made or shipped in one orientation and must be hoisted by both ends and the ends moved independently of one another into another orientation, such as from a horizontal transportation orientation to a vertical installation orientation, or from a vertical manufacturing orientation to a horizontal storage or transportation orientation.
Hoist rings of various designs that are intended to be attached to heavy loads are well known. See, for example, Alba U.S. Pat. No. 6,953,212, Alba U.S. Pat. No. 6,267,422, Tsui U.S. Pat. No. 5,732,991, Alba U.S. Pat. No. 6,199,925, Tsui et al. U.S. Pat. No. 5,979,954, and Tsui et al. U.S. Pat. No. 6,022,164, each of which is hereby incorporated herein by reference as though fully set forth hereat. The structures of these hoist rings are such that the bails to which lifting lines connect are capable of swiveling and pivoting omni-directionally within at least approximately a hemisphere so as to align the bail with the load that is applied to it. This hemispheric envelope is generally symmetrical around the swiveling axis of the hoist ring. The advantage of a hoist ring that exhibits such hemispheric omni-directionality is that the hoist ring has the same load bearing capacity regardless of the direction of the load within the hemispheric envelope. By contrast, eyebolts have a maximum capacity only when loads are applied along the major axis. The load capacity of an eyebolt falls off quickly as the direction of the applied load changes from axial to an angle to the major axis of the eyebolt.
Hoist rings are classified as critical lifting devices, and are subject to rigorous safety standards. Quality controls on manufacturing operations, testing, and safety margins for strength are very stringent. They must be safe to use by workers at construction sites with a minimum of specialized instruction. Hoist rings should be rugged and simple so that it is difficult to damage them or use them improperly.
These and other difficulties of the prior art have been overcome according to the present invention.